1. Field of the Invention
This innovation pertains to compressors utilizing linear motor drive and clearance seals. These compressors utilize a linear motor to drive the piston and a spring to provide energy storage to create a mechanical resonant moving mass (piston assembly) and axial restoring force to properly locate the piston.
2. Prior Art
The typical gas bearing compressor system utilizes a piston that is allowed to move radially with little resistance, which in turn allows the gas bearing to center the piston in the cylinder and prevent piston to cylinder contact. This type of gas bearing system is described in patent U.S. Pat. Nos. 6,293,184 and 5,525,845. Another method for preventing piston to cylinder contact is to use a “planar spring” supported piston. This system utilizes flat springs to provide a very stiff radial spring constant that will guide the piston and prevent contact with the cylinder. A key difficulty of this latter design is obtaining proper alignment while securing the springs. The typical radial gap between piston and cylinder in these oil free clearance seals is 0.0001 to 0.0003 inches. This mechanical alignment approach requires expensive precise tooling and significant labor costs, and is hence incompatible with a low cost, mass produced device. If this alignment is not correct, the springs, which are very stiff in the radial direction, will force the piston against the cylinder and cause premature wear and failure.